ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Offering Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Offering Costs [Abstract]
Maximum percentage of aggregate subscriptions accepted during initial and continuous offerings	2.50%
Maximum potential remaining reimbursement for offering costs	$ 35,600,000	$ 36,400,000
Unreimbursed offering costs	57,600	65,550
Offering costs payable	$ 57,600	$ 65,550